Symmetrical frequency doubler



June 5, 1956 H. E. Hos'rlcKA ETAL 2,749,499

SYMMETRICAL FREQUENCY DOUBLER Filed June 14, 1951 HAROLD HosT/KA Ew/5 E.@Ec/(ETT mvENroRs ATTORNEY SYMIWETRICAL FREQUENCY DOUBLER Harold E.Hosticka, Denver, and Lewis R. Beckett, Evergreen, Colo.

Application `lune 14, 1951, Serial No. 231,642

6 claims. (ci. 321-4) l (Granted under Titia 35, U. S. Code (i952), sec.266) The linvention described herein may be manufactured and used by orfor the Government of the United States for governmental purposeswithout the payment to us of any royalty thereon in accordance with theprovisions of the Act of April 30, 1928 (Ch. 460, 45 Stat. L. 467).

This invention relates to electrical systems, and more particularly tomeans for and methods of doubling frequency of alternating-currentsignals.

An object of this invention is to provide an improved and inexpensivemeans for and method of doubling the frequency of an alternating-currentsignal and obtaining a symmetrical output which may be'used as such ormay easily be coverted to a sinusoidal wave form.

Other objects will be apparent from the following description andaccompanying drawings wherein:

Figure l is a circuit diagram of a preferred embodiment of theinvention.

Figure 2 is a graphical representation of the wave forms of signalsobtained at various points in the process of doubling the frequency ofan input signal.

in a preferred embodiment of the invention illustrated in Figure l,means are provided for converting a single alternating current signalshown at a in Figure 2, into two phase components substantially 90degrees apart as shown at b and c in Figure 2. This means mayconveniently take the form of a phase divider i with three outputterminals 2, 3, and l. The leading phase component, shown at b in Figure2, may conveniently appear between the terminal 2 and the neutral 3, andthe lagging phase cornponent, shown at c in Figure 2, may appear betweenthe terminal i and the neutral 3.

Means are provided for dividing each of the two phase components b and cinto positive and negative parts d, e, f and g as shown in Figure 2.Conveniently, a pair of rectiliers 7 and 8, one with its anode and theother with its cathode connected to the terminal 2, may be used todivide the leading phase component b. Similarly, another pair of rectersit) and l1, one with its anode and the other with its cathode connectedto the terminal 4, may be used to divide the lagging phase component c.The term-s anode and cathode are used merely to indicate the directionof flow of current through the rectiiiers, and are not a limitation uponthe type of rectiiiers that may be used. All types of rectiiiers may beused in various embodiments of the invention.

Means are also provided for adding the positive half d of the leadingphase component to the negative half g of the lagging phase component.If the cathode of the rectifier 7 is connected to the terminal 2, andthe anode of the rectifier iti is connected to the terminal 4, this maybe done by connecting the anode of the rectifier 7 through two resistors13 and 14 to the cathode of the rectifier 10. The two resistors 13 and14 are connected to each other at a terminal 16.

Similarly, means are provided for adding the negative half e of theleading phase component to the positive half f of the lagging phasecomponent. If the anode of the rectifier 8 is connected to the terminal2 and the cathode nie@ Se@ een@ appreciable quantity of the secondharmonic.

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of the rectifier 11 is connected of the terminal 4, this may be done byconnecting the cathode of the rectier 8 through two resistors 2t) and 21to the anode of the rec-v tier il. The two resistors 2) and 21 areconnected together at a terminal 22. Y

Those skilled in the art will appreciate that the resistors mentionedabove may, in actual practice, take the form of `the resistance which isinherent in the other elements of the device, for example, therectitiers. The resistors need not be separate elements.

rvThe sum signals obtained by the two additions of positive to negativehalves of the two phase components, are the distorted alternatingcurrent signals illustrated at l1 and z' in Figure 2.

Means are also provided for combining the two sumk signals, as byinverting one of the signals and adding them. Preferably this is donewith a pair of so-called differencing resistors 25 and 26 which areconnected between the terminals i6 and 22, and which are connected toeach other and to the neutral terminal 3 at a tap 27. The combinedsignal which may be taken from the output:v terminals i6 and 22 isillustrated at j in Figure 2.

The wave form of the output j is pointed, is composed of approximatelystraight lines, and is free from any It may be used directly in manydevices, but is easily converted to a. sinusoidal form when that isdesired. The output is fed through a conventional filter. Since there isno second harmonic, the filter need not have a cut-olic frequency nearthe fundamental. it is apparent, therefore, that this invention puts outa signal which is twice the frequency of the input, which issymmetrical, and which is more easily converted to sinusoidal wave formthan the output of other frequency doublers known to the art.

it will be understood that the embodiment shown and described is purelyillustrative and that modifications may be made therein withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:

l. In a system for obtaining a signal of twice the frequency of twoalternating current phase components substantially degrees apart, meansfor dividing the positive from the negative half of each of said phasecornponents, means for adding the positive half of the first and thenegative half of the second of said phase com ponents to obtain adistorted alternating current signal, means for adding the negative halfof the rst and the positive half of the second of said phase componentsto obtain another distorted alternating current signal, and means foradding the two distorted alternating current signals in opposite senseswhereby a symmetrical alternating current signal is obtained.

2. In an electrical frequency doubler, phase splitting means forobtaining from an alternating input wave two alternating wavessubstantially 90 degrees apart in phase, said phase splitting meanshaving rst, second and neutral terminals, a first rectifier with anodeconnected to said rst terminal, a second rectifier with cathodeconnected to said first terminal, a third rectier with anode connectedto said second terminal, and a fourth rectifier with cathode connectedto said second terminal, the cathode of said first rectifier and theangle of said fourth rectifier being connected to a first outputterminal, the anode of said second rectifier and the cathode of saidthird rectifier being connected to a second output terminal each of saidoutput terminals being respectively connected through a resistor to saidneutral terminal the connections from said first and second terminals ofsaid phase splitting means to said first and second output terminalsrespectively through said four rectiers each including resistance.

3. A system for deriving, from two fundamental frequency alternatingcurrent phases substantially 90 apart,

an alternating current of twice the fundamental frequency, said systemcomprising (a) means for dividing each phase into separate spacedpositive half-cycle and spaced negative half-cycle currents of thefundamental frequency, (b) means for separately combining the spacedpositive half-cycle current divided from each phase with the negativehalf-cycle current divided from the other phase to produce distortedalternating currents of the fundamental frequency, and (c) means forinverting one of the two distorted alternating currents of fundamentalfrequency and adding it to the other to produce a symmetricalalternating current of twice the fundamental frequency.

4. A system according to claim 3, said inverting and adding means (c)comprising ditferencing resistance means interconnecting said separatelycombining means (b).

5. In a system for doubling the frequency of an alter hating signal, incombination, means for dividing said signal into 'first and second phasecomponents substantially 90 degrees apart in phase, means for rectifyingeach of said phase components into positive and negative halves, meansfor adding the positive half of said rst phase component to the negativehalf of said second phase cornponent to obtain a first sum signal, meansfor adding the negative half of said rst phase component to the positivehalf of said second phase component to obtain a second sum signal, andmeans for adding said rst sum signal to said second sum signal inopposite senses, whereby a wa've form substantially free of secondharmonic is obtained.

6. Apparatus for doubling the frequency of an alternating currentsignal, comprising, in combination, means for dividing said signal intorst and second phase components substantially 90 apart in phase and notnecessarily of the same amplitude, means for rectifying one of saidphase components into positive and negative halves each of substantiallyequal amplitude, means for rectifying the other of said phase componentsinto positive and negative halves each of substantially the sameamplitude but not necessarily of the same amplitude as the halves of thefirst of said phase components, means for adding the positive half ofthe rst phase component to the negative half of the second phasecomponent to obtain a first sum signal, means for adding the negativehalf of the first phase component to the positive half of the secondphase component, to obtain a second sum signal, and means for invertingone of said sum signals and adding it to the other of said sum signals,whereby a symmetrical wave form of uniform amplitude and substantiallyfree of second harmonic is obtained.

References Cited in the le of this patent UNITED STATES PATENTS 736,884Shoemaker Aug. 18, 1903 1,394,325 Meyer Oct. 18, 1921 1,505,234 AkersAug. 19, 1924 2,085,515 Steinmetz June 29, 1937 2,440,465 Ferguson Apr.27, 1948 2,461,861 Walker Feb. 15, 1949

